The present invention relates to a manifold having built therein a thermoelectric module of a type having a Peltier effect.
In recent years, depletion of the ozone layer in contact with fluorinated hydrocarbon gas has come to be a global problem and immediate development of refrigerating apparatuses that do not use fluorinated hydrocarbons is desired. As one of the refrigerating apparatuses that do not use fluorinated hydrocarbons the refrigerating apparatus utilizing a thermoelectric module has now come to be spotlighted.
The thermoelectric module includes a Peltier module or a component known as a thermoelectric module and having two heat transfer surfaces which are heated and cooled, respectively, when an electric current is applied thereto. In other words, in the thermoelectric module, one of the heat transfer surfaces acts as an exothermic surface whereas the other of the heat transfer surfaces acts as an endothermic surface.
The refrigerating apparatus utilizing the thermoelectric module is disclosed in, for example, the published International Application WO92/13243, in which the thermoelectric module is built in a manifold having two cavities defined on respective sides of the thermoelectric module. One of the cavities facing the exothermic surface of the manifold is coupled with a closed circuit comprised of a heat exchanger and a pump whereas the other of the cavities facing the endothermic surface is similarly coupled with a closed circuit comprised of a heat exchanger and a pump. In this way, a circulating circuit including the heat transfer surface on an endothermic side of the thermoelectric module and a circulating circuit including the heat transfer surface on a cooling side are defined, and a heat transfer medium including water as a principal component is circulated therein. A desired refrigeration can be accomplished by means of the heat exchanger installed on one of these two circulating circuits and on the cooling side.
Although the invention disclosed in WO92/13243 referred to above is a technology in which the thermoelectric module is utilized to achieve a practical refrigeration, it merely discloses a basic structure of the refrigerating apparatus and involves a number of problems to be solved in order for that invention to be practically applicable to a refrigerator or the like.
In other words, the refrigerating apparatus utilizing the thermoelectric module has a lower refrigerating efficiency than that exhibited by the traditional refrigerating apparatus operating with a fluorinated hydrocarbon gas.
The technology disclosed in WO92/13243 involves a problem of how the contact between the heat transfer medium and the heat transfer surfaces of the thermoelectric module should be smoothened to increase the refrigerating efficiency. As an improving means for enhancing a heat exchange between the thermoelectric module and the heat transfer medium, the invention disclosed in the published International Application WO95/31688 (PCT/AU95/00271) is known, in which a stirrer blade is disposed within the cavity of the manifold to enhance contact between the heat transfer medium and the heat transfer surfaces of the thermoelectric module and which is expected to exhibit a high heat transfer efficiency as compared with the traditional one.
However, WO95/31688 has failed to disclose a specific means for driving the stirrer blade within the cavity. In otherwords, although the use of the stirrer blade within the cavity is effective to alleviate the previously discussed problem to a certain extent, no specific means for driving the stirrer blade within the cavity is disclosed.
Also, in order for the stirrer blade within the cavity to be driven, the use of a bearing seal for a rotary shaft is necessitated to countermeasure against leakage of the heat transfer medium. In addition, in order for the heat transfer medium to be supplied into the narrow cavity, complicated flow passages need be formed within the cavity, resulting in a problem associated with a relatively large loss of pressure.
The present invention has therefore been developed with the foregoing problems taken into consideration and is intended to provide a manifold in which a thermoelectric module having a heat exchange efficiency increased by the provision of a stirrer member for stirring a fluid within the cavity is incorporated.
Another object of the present invention is to provide a manifold with the thermoelectric module built therein, wherein the heat exchange efficiency is increased by enhancing contact between the heat transfer medium and the heat transfer surfaces of the thermoelectric module and which has a high reliability with a minimized loss of pressure.
In order to accomplish the foregoing objects, the manifold having the thermoelectric module built therein in accordance with the present invention is characterized by comprising a thermoelectric module having exothermic and endothermic (heat transfer) surfaces, which are heated and cooled, respectively, when an electric current is supplied thereto; a manifold body accommodating therein the thermoelectric module, said manifold having a cavity defined therein for entry of a fluid medium in cooperation with at least one of the exothermic and endothermic surfaces and having a hollow defined therein so as to extend from an outside to the cavity; a stirring member disposed within the manifold body and having a stirring portion integrated together with a rotor for stirring the fluid medium within the cavity; and a stator mounted externally on the manifold body; said rotor and said stator cooperating with each other to form a motor, said stirring member when electric power is supplied to the stator rotating within the cavity to allow the fluid medium to flow past an interior of the rotor towards the cavity.
In this structure, since the stirring member rotates within the cavity when electric power is supplied to the external stator, the opportunity of the fluid medium contacting the thermoelectric module increases to thereby increase the heat exchange efficiency. Also, since no shaft seal is needed, leakage of the fluid medium is small, resulting in increase in reliability. In addition, since the fluid medium flows through the interior of the rotor to reach the cavity, a fluid passage is straight and a loss of pressure is small.
If an opening is provided at a center portion of the rotor and the fluid medium flows past such opening, the flow of the fluid medium will be rectilinear and the loss of pressure can further be reduced.
Also, the manifold having the thermoelectric module built therein in accordance with the present invention is characterized by comprising a thermoelectric module having exothermic and endothermic surfaces, which are heated and cooled, respectively, when an electric current is supplied thereto; a manifold body accommodating therein the thermoelectric module, said manifold body having a cavity defined therein for entry of a fluid medium in cooperation with at least one of the exothermic and endothermic surfaces and having a hollow defined therein so as to extend from an outside to the cavity; and a stirring member disposed within the manifold body for stirring the fluid medium within the cavity, said stirring member having a throughhole defined therein, said through hole being provided with a blade member, the fluid medium being allowed to flow through the throughhole towards the cavity.
In this structure, since the fluid medium reaches the cavity through the throughhole defined in the stirring member, the flow passage for the fluid medium is rectilinear and the loss of pressure is small. Also, since the vanes disposed in the throughhole exhibit a function similar to vanes of an axial flow pump to urge the fluid medium to thereby vigorously contact the thermoelectric module, the heat exchange efficiency between the thermoelectric module and the fluid medium increases.
In addition, if the stirring member is rotatable about an axis intersecting any one of the endothermic and exothermic surfaces, the fluid medium flows in a direction intersecting the endothermic or exothermic surface and, therefore, the opportunity of the fluid medium to contact the endothermic or exothermic surface increases to thereby increase the heat exchange efficiency.
In the event that the stirring member has a center portion having a throughhole defined therein and in that a bearing member is supported within the through hole by means of ribs and that the bearing member is inserted in a support shaft fixed relative to the manifold body to thereby support the stirring member for rotation, the fluid medium having flown through the throughhole is directly introduced into the cavity and then vigorously contacts the thermoelectric module, resulting in increase of the heat exchange efficiency.
Where the ribs for supporting the bearing member are provided with respective inclined surfaces, the fluid medium can be urged towards the cavity as the ribs rotate. In other words, since the ribs exhibit a function similar to an axial flow pump to pump the fluid medium towards the cavity, the fluid medium can vigorously contact the thermoelectric module, resulting in increase of the heat exchange efficiency.
Also, where the bearing member has a hole or a tapered portion defined therein and having a diameter enlarged outwardly at one end face thereof, the fluid medium enters inside the bearing member to thereby lubricate the bearings and, therefore, rotation of the stirring member can become smooth.
Cavities may be defined respectively between the thermoelectric module and the endothermic surface and between the thermoelectric module and the exothermic surface, with the stirring member provided in each of the cavities, at least one of the stirring members being provided with magnets, so that rotation of one of the stirring members can be transmitted to the other of the stirring members by means of a magnetic force. This structure is effective in that since rotation of only one of the stirring members is sufficient to simultaneously rotate the stirring members on the heating and cooling sides, respectively, the number of component parts can be reduced to make it possible to manufacture the manifold in a compact size. Also, since driving power can be transmitted between the stirring members in a non-contact manner, it is possible to secure independence of those cavities with no fear of the heat transfer medium on the heating side and the heat transfer medium on the cooling size being mixed together.
If the manifold body covers only one of the heat transfer surfaces of the thermoelectric module and the other of the heat transfer surfaces of the thermoelectric module is held in abutment with a heat conductive plate, an object to be cooled can be directly cooled by the heat conductive plate.